Approximate tight-binding sum rule for the superconductivity related change of c-axis kinetic energy in multilayer cuprate superconductors

摘要

We present an extension of the c-axis tight-binding sum rule discussed byChakravarty, Kee, and Abrahams [Phys. Rev. Lett. 82, 2366 (1999)] that appliesto multilayer high-Tc cuprate superconductors (HTCS) and use it toestimate--from available infrared data--the change below Tc of the c-axiskinetic energy, Hc, in YBa2Cu3O(7-delta) (delta=0.45,0.25,0.07), Bi2Sr2CaCu2O8,and Bi2Sr2Ca2Cu3O10. In all these compounds Hc decreases below Tc and exceptfor Bi2Sr2CaCu2O8 the change of Hc is of the same order of magnitude as thecondensation energy. This observation supports the hypothesis that inmultilayer HTCS superconductivity is considerably amplified by the interlayertunnelling mechanism.